Nearly million people displaced by CAR conflict - UN
The number of internally displaced people in the Central African Republic (CAR) has more than doubled to 935,000 since December, the UN says.
Around 500,000 have fled their homes in the capital Bangui alone - almost half the city's population. Some 60% of those displaced are children.
The UN also warned the escalating violence was hampering efforts to reach "those in need of urgent assistance".
The conflict has pitted Christian and Muslim militias against each other.
The CAR is ruled by Muslim ex-rebel leader Michel Djotodia who seized power last March, forcing then-President Francois Bozize, who came from the majority Christian population, to flee into exile.
The African Union has sent nearly 4,000 troops while France, the former colonial power, has also deployed 1,600 soldiers there.
Many foreign governments have begun to evacuate their citizens.
'Hiding in the bush'
The UN's refugee agency warned the delivery of aid relief was being "severely limited" by attacks on civilians, looting and the presence of armed militia at refugee camps.
"Our staff report that people are hiding in the bush, fearing fresh attacks," the agency said in a statement.
It said the number of people sheltering at a makeshift camp at Bangui airport had doubled to around 100,000 over the last week.
The UN said additional and more effective troops were needed as a matter of urgency.
French and African Union troops at the airport have been unable to provide sufficient protection for aid deliveries to be flown out to surrounding areas.
The UN is seeking $152m (£92m) for a 100-day emergency plan to tackle the humanitarian crisis.
Medecins Sans Frontieres, the only medical provider at the Bangui airport camp, confirmed it had been forced to drastically reduce its activities there following two days of shooting, which killed two children and wounded dozens of people.
The charity said it was now treating only the most severe cases.
Earlier this week, the UN warned the violence had sunk "to a vicious new low" as children were mutilated and beheaded in revenge attacks.
Thousands of foreign nationals are still waiting to be evacuated, including an estimated 2,000 Nigerians camped out in the Nigerian embassy grounds in Bangui.
Abubakar Abba Kasum, a Nigerian living in Bangui, told the BBC's Hausa Service that Nigerians had been gathering at the embassy for the last 15 days and the situation was becoming unhygienic.
Embassy officials had told them that two planes with capacity to take 1,100 people in total were due to land in Bangui on Friday, Mr Kasum said.
They were told more planes would be sent to collect those not on the first flights, he said.
Thousands of Chadians living in the CAR have already fled abroad in recent weeks. They have been accused by some of backing Mr Djotodia's forces.
Similar accusations have been levelled against the Chadian contingent of the African peacekeeping force in the CAR.